Metal clips are commonly used to attach a fish hook or lure to the end of a fishing line, thereby avoiding the need to cut the line and re-tie a new knot every time a hook or lure is changed. Such clips must be small and lightweight so as not to be visible to fish or impede the movement of the fishing lure, and must also be strong and easy to open while resisting unintentional opening.
A typical clip for attaching a lure to a fishing line comprises an elongate body formed from a single strand of resilient, corrosion resistant wire and having loops at its opposite ends. One loop can be opened for attachment to the eyelet of a fish hook or lure, and the other loop preferably remains closed and is adapted to connect to a fishing line by a knot or an intermediate swivel connection. The loop which connects to the lure is typically closed by applying a force to a biasing arm member having a U-shaped hook at its end, forcing the hook to wrap around a portion of the clip and be retained in position by the biasing force of the arm. Opening the clip is accomplished by squeezing the loop to overcome the biasing force and allow the U-shaped hook to spring free from the remainder of the clip.
A number of different clips of this type are known in the prior art, however none has proved to be completely satisfactory. One example of a known clip is disclosed in U.S. Pat. No. 5,655,329 to Yong-Set, issued Aug. 12, 1997. Yong-Set discloses a straight-backed clip having the features described above, comprising an elongate body having loops at its opposite ends, and having a straight support member bridging the two loops. The smaller loop of the Yong-Set clip has an extension in the form of a ring which is substantially perpendicular to the two loops comprising the clip. The clip is closed by passing the U-shaped hook through the ring and hooking it around the support member. While the Yong-Set clip is designed to resist unintentional opening, even after becoming deformed by a relatively large tensile load, it has been found to be relatively difficult to open since the hook must be disengaged from the back member of the clip and passed through the ring before the clip will open.
U.S. Design Pat. No. D256,942 to McMickle discloses a straight-backed clip which eliminates the ring of the Yong-Set clip and is therefore of simpler construction. The McMickle clip is also closed by squeezing the biasing arm member of the clip so that the hook will wrap around the straight support member of the clip and be retained by the biasing force of the arm member. While the McMickle clip is simple in design, it has been found that when the clip is opened the biasing force is such that the biasing arm does not spring back far enough to permit the easy addition or removal of a fishing lure or hook. It is necessary to bend the biasing arm backward to adequately open the clip, and repeating this procedure results in fatigue of the metal and eventual breakage of the clip when it becomes lodged against an underwater obstacle or when it hooks a fish. Furthermore, the biasing force present in the biasing arm when the clip is in the closed position is minimal and may result in the unintentional opening of the clip. The lower biasing force of the biasing arm is due to the fact that it must travel to the opposite side of the straight back member before it can engage the member to close the clip, resulting in a great amount of stress in the loop formed between the biasing arm and the straight back member. This stress also causes the biasing arm not to spring back far enough when the clip is opened.
Another clip is shown in U.S. Design Pat. No. D393,688 to Essad, issued Apr. 21, 1998. In the Essad clip, the larger loop is formed by connecting the U-shaped hook of the biasing arm member to the smaller loop rather than the support member of the clip. Because the hook at the end of the biasing arm is not U-shaped, it releases with very low loads resulting in loss of fishing lures and fish. Additionally, the larger diameter of the loop results in a clip that has lower tensile strength. This causes the clip to deform very easily, thereby weakening the mechanical integrity of the clip and resulting in the eventual loss of lures and fish. The larger radius of the loop forming the biasing arm also results in lower biasing force in the arm.